Physiology of Feeding and Satiety Flashcards
(40 cards)
what is energy homeostasis
Physiological process whereby energy intake is matched to energy expenditure over time
what is obesity
metabolic syndrome characterised by central obesity, dyslipidemia, insulin resistance= type 2 diabetes, cardiovascular disease
how is obesity viewed
as a disease and a disability
what are the major factors influencing obesity
genetics; susceptibility genes
environment
what diseases are associated with obesity
type 2 diabetes, hypertension, heart attack, certain cancers, osteoarthritis, heart disease, resp disease (sleep apnea), stroke, dementia, fatty liver
why do we need fat
energy storage, prevention of starvation, energy buffer during prolonged illness
why does the brain make it difficult to lose weight
increased body fat alters brain function, induces re-programming where it view the extra weight as normal and dieting as a threat to survival
how does the CNS influence energy balance and body weight
behaviour (feeding and physical activity)
ANS (regulates energy expenditure)
neuroendocrine system (secretion of hormones)
what part of the brain is responsible for fat storage
hypothalamus
what three basic concepts underlie the control of energy intake and body weight
satiety signalling, adiposity negative feedback signalling,
food reward
what is satiation
sensation of fullness generated during a meal
what is satiety
period of time between termination of one meal and the initiation of the next
what is adiposity
the state of being obese
when do satiation signals increase
during meals to limit meal size
what are the satiation signals
cholecystokinin (CCK), peptide YY (PYY3-36), Glucagon-like peptide (GLP-1), oxyntomodulin (OXM), obestatin
what does cholecystokinin do and what secretes it
secreted from enteroendocrine cells
in duodenum and jejunum. Released in proportion to lipids and
proteins in meal. Signals via sensory nerves to hindbrain and
stimulates hindbrain directly (nucleus of solitary tract (NTS)).
what does peptide YY do and what secretes them
secreted from endocrine mucosal L-
cells of G-I tract. Levels increase rapidly post-prandially. Inhibits
gastric motility, slows emptying and reduces food intake (Hypo).
what does glucagon like peptide 1 do
product of pro-glucagon
gene. Also released from L cells in response to food ingestion.
Inhibits gastric emptying and reduces food intake (Hypo, NTS)
what does oxyntomodulin do and what secretes it
Also from pro-glucagon gene and
released from oxyntic cells of small intestine after meal. Acts
to suppress appetite – mechanism unclear.
what does obestatin do and what secretes it
peptide produced from gene that encodes ghrelin
and released from cells lining stomach/small intestine.
Suggested to reduce food intake – may act to antagonise the
actions of ghrelin – actions unclear at present.
what is ghrelin- what secretes it and what does it do
a hunger signal- Octanoylated peptide, produced and secreted by
oxyntic cells in stomach. Ghrelin levels increase before meals
and decrease after meals. Levels are raised by fasting and
hypoglycaemia.
Peripheral ghrelin stimulates food intake (Hypo) and decreases
fat utilization
what central appetite controllers work to increase food uptake
Glutamate, Gaba and opioids increase food intake when
injected into hypothalamic centres - effects modest/short
lasting
what central appetite controllers work to suppress food uptake
Monoamines act to suppress food intake - many drugs
developed to act on these systems - most withdrawn due
to side-effects.
what are adiposity signals
hormones produced in peripheral tissues that act on hypothalamic neurons to tell the brain the status of body fat stores
